The proposed study has three major objectives: (1) to provide a more complete assessment of the character, scope, and dynamics of female delinquency than has been possible using more typical official or self-report methods; (2) to analze, through the use of a longitudinal design, the developmental processes which account for females' initial entry into delinquency, the period of peak involvement, as well as the processes which result in their maturing out; and (3) to examine change over time in the extent and nature of girls' participation in illegal activity. An important focus within each of these objectives is the role of the peer group in producing such delinquent outcomes. To accomplish these research objectives, the study is designed as a longitudinal analysis of the delinquency of adolescents between the ages of 11 and 21, based on a sample of neighborhood surveys of residences in Toledo, Ohio. The design calls for three interview waves which will permit three basic types of analysis: inter-cohort, intra-cohort, and the establishment of trends at various age levels. Conceptually, the research is informed by an analysis of variables which relate to the delinquent act itself (types of acts, magnitude, meaning, spatial patterning, active/passive roles, social context, degree of planning, associated technology, verbalized motives), those which preceed the act (characteristics of group formation, quality of group life, the influence of "best friends," the nature of peer influences, group changes, status positions within the group, the effect of school, dating, economic and family influences), and those which proceed the act (the impact of sanctions imposed by the family, school, and juvenile justice systems, and the manner in which these may differ for males and females in both their imposition and their subsequent ramifications).